Cosmic ray isotope measurements with a new Cerenkov X total energy telescope

Measurements of the isotopic composition of cosmic nuclei with Z = 7-20 are reported. These measurements were made with a new version of a Cerenkov x total E telescope. Path length and uniformity corrections are made to all counters to a RMS level 1%. Since the Cerenkov counter is crucial to mass measurements using the C x E technique - special care was taken to optimize the resolution of the 2.4 cm thick Pilot 425 Cerenkov counter. This counter exhibited a beta = 1 muon equivalent LED resolution of 24%, corresponding to a total of 90 p.e. collected at the 1st dynodes of the photomultiplier tubes

Cosmic ray charge and energy spectrum measurements using a new large area Cerenkov x dE/dx telescope

In September, 1981, a new 0.5 square meter ster cosmic ray telescope was flown to study the charge composition and energy spectrum of cosmic ray nuclei between 0.3 and 4 GeV/nuc. A high resolution Cerenkov counter, and three dE/dx measuring scintillation counters, including two position scintillators were contained in the telescope used for the charge and energy spectrum measurements. The analysis procedures did not require any large charge or energy dependent corrections, and absolute fluxes could be obtained to an accuracy approximately 5%. The spectral measurements made in 1981, at a time of extreme solar modulation, could be compared with measurements with a similar telescope made by our group in 1977, at a time of minimum modulation and can be used to derive absolute intensity values for the HEAO measurements made in 1979 to 80. Using both data sets precise energy spectra and abundance ratios can be derived over the entire energy range from 0.3 to greater than 15 GeV/nuc

Digital or Printed Textbooks: Which do Students Prefer and Why?

Despite the fact the many textbook publishers offer several of their titles in digital format, the sale of e-textbooks have been less than stellar. This study investigates factors in the adoption of e-textbooks. Specifically, it examines students’ preferences toward printed versus electronic textbooks, and why they prefer one to the other. In general, students still prefer printed textbooks to electronic textbooks. The primary reason for their preference was because the students simply prefer print to digital. This study helps both textbook publishers and educators to better understand the reasons for e-textbook adoption and help determine ways to communicate the benefits of e-textbooks

Progress on Autosomal Dominant Polycystic Kidney Disease

Introduction: Autosomal dominant polycystic kidney disease (ADPKD) is the most common life threatening hereditary disease of the kidney. It is a systemic disease characterized by multiple, bilateral renal cysts that result in massive renal enlargement and progressive functional impairment. This review discusses the current understanding of the epidemiology, genetics, clinical manifestations, natural history of the disease, the accuracy and reliability of diagnostic approaches, renal replacement therapy and emerging therapeutic strategies that are being evaluated in ADPKD. Review: ADPKD is a genetically heterogeneous disease with significant inter-familial and intra-familial variability. The responsible genes were localized to separate loci on chromosome 16 (PKD1 gene) accounting for the majority of ADPKD cases, and chromosome 4 (PKD2 gene) accounting for the remainder. Each child of an affected parent has a 50% chance of inheriting the mutated gene, which is completely penetrant. Clinical manifestations include renal and cyst enlargement, impaired urine concentration capacity, hematuria, nephrolithiasis, proteinuria, hypertension, polycystic liver disease, abdominal wall hernia and intracranial aneurysms. The diagnosis of ADPKD usually relies on renal imaging. Ongoing research has engendered crucial insight into the disease’s underlying genetic, cellular and pathogenetic mechanisms and made possible the design and implementation of clinical trials testing promising treatments. Renin Angiotensin Aldosterone System (RAAS) blockade, vasopressin antagonists, somatostatin, rapamycin, sirolimus and everolimus are currently being evaluated for a potential therapeutic role in the management of ADPKD. Conclusion: Current clinical trials investigating multiple therapeutic targets bring hope for treatments that may impede the progression of ADPKD. Keywords: ADPKD, autosomal dominant polycystic kidney disease, kidney failur

An Analysis of Online Customer Complaints in Multiple Sectors of the Hotel Industry

The Internet has become a highly used tool for communication. Through the use of online communities consumers are able to view as well as leave comments regarding their experiences. These comments can either be positive or negative. By examining the customer complaining behavior, the purpose of this study is to identify the differences between negative online complaints against luxury hotels and mid-scale hotels, and to provide managers with some insights to help them respond properly to different online complaints. Using both qualitative and quantitative approaches, online complaints will be analyzed. The findings of this study are expected to help hotel managers properly respond to online complaints

WiFi Availability and Accessibility as Stated on Hotel Websites

Competition among hotels is increasing. As such, hotels are constantly looking for ways to increase both their competitive advantage and guest satisfaction. Hotels have discovered ways to do this through the use of technologies such as wireless networks. Wireless networks have the potential to provide guests with additional amenities as well as allow for greater productivity among staff members. This can both increase a hotel’s competitive advantage, and satisfy guest expectations. The purpose of this exploratory study, therefore, is to determine if hotels are taking advantage of this opportunity by promoting wireless internet availability via their property’s website and using it as a tool to attract customers. The findings of this study indicate that hotels are using their websites to provide information about availability of wireless access. However, limited information is indicated on the websites as to the location of access points and the charges related with use of the service

Atomistic Theory of Coherent Spin Transfer between Molecularly Bridged Quantum Dots

Time-resolved Faradary rotation experiments have demonstrated coherent transfer of electron spin between CdSe colloidal quantum dots coupled by conjugated molecules. We employ here a Green's function approach, using semi-empirical tight-binding to treat the nanocrystal Hamiltonian and Extended Huckel theory to treat the linking molecule Hamiltonian, to obtain the coherent transfer probabilities from atomistic calculations, without the introduction of any new parameters. Calculations on 1,4-dithiolbenzene and 1,4-dithiolcyclohexane linked nanocrystals agree qualitatively with experiment and provide support for a previous transfer Hamiltonian model. We find a striking dependence on the transfer probabilities as a function of nanocrystal surface site attachment and linking molecule conformation. Additionally, we predict quantum interference effects in the coherent transfer probabilities for 2,7-dithiolnaphthalene and 2,6-dithiolnaphthalene linking molecules. We suggest possible experiments based on these results that would test the coherent, through-molecule transfer mechanism.Comment: 12 pages, 9 figures. Submitted Phys. Rev.

Using data assimilation to study extratropical Northern Hemisphere climate over the last millennium

Climate proxy data provide noisy, and spatially incomplete information on some aspects of past climate states, whereas palaeosimulations with climate models provide global, multi-variable states, which may however differ from the true states due to unpredictable internal variability not related to climate forcings, as well as due to model deficiencies. Using data assimilation for combining the empirical information from proxy data with the physical understanding of the climate system represented by the equations in a climate model is in principle a promising way to obtain better estimates for the climate of the past. <br><br> Data assimilation has been used for a long time in weather forecasting and atmospheric analyses to control the states in atmospheric General Circulation Models such that they are in agreement with observation from surface, upper air, and satellite measurements. Here we discuss the similarities and the differences between the data assimilation problem in palaeoclimatology and in weather forecasting, and present and conceptually compare three data assimilation methods that have been developed in recent years for applications in palaeoclimatology. All three methods (selection of ensemble members, Forcing Singular Vectors, and Pattern Nudging) are illustrated by examples that are related to climate variability over the extratropical Northern Hemisphere during the last millennium. In particular it is shown that all three methods suggest that the cold period over Scandinavia during 1790–1820 is linked to anomalous northerly or easterly atmospheric flow, which in turn is related to a pressure anomaly that resembles a negative state of the Northern Annular Mode

Clinical implications of vitamin B₁₂ as redox-active cofactor

Vitamin B12 is a redox-active compound containing a cobalt atom that cycles between oxidation states. Superoxide scavenging induces its oxidation, disabling activation of the enzymes methionine synthase and methylmalonyl-CoA mutase, disrupting gene expression and energy production. High-dosed vitamin B12 may be clinically used to reduce oxidative stress and preserve cofactor functions